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SubjectRe: [PATCH v2] perf trace: Fix missing handling of --call-graph dwarf
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On 01/15/2018 03:16 PM, Arnaldo Carvalho de Melo wrote:
> Em Mon, Jan 15, 2018 at 10:57:52AM -0300, Arnaldo Carvalho de Melo escreveu:
>>> [root@f27 perf]# ./perf trace --no-syscalls --max-stack 4
>>> -e probe_libc:inet_pton/call-graph=dwarf/ ping -6 -c 1 ::1
>>> PING ::1(::1) 56 data bytes
>>> 64 bytes from ::1: icmp_seq=1 ttl=64 time=0.020 ms
>>>
>>> --- ::1 ping statistics ---
>>> 1 packets transmitted, 1 received, 0% packet loss, time 0ms
>>> rtt min/avg/max/mdev = 0.020/0.020/0.020/0.000 ms
>>> 0.000 probe_libc:inet_pton:(7ffbc5f768a0))
>>> __inet_pton (inlined)
>>> gaih_inet.constprop.7 (/usr/lib64/libc-2.26.so)
>>> __GI_getaddrinfo (inlined)
>>> main (/usr/bin/ping)
>>> [root@f27 perf]#
>>>
>>>
>>> --> Dwarf call graph and --max-stack 4 is also honoured.
>>
>> [root@jouet ~]# perf trace --no-syscalls -e probe_libc:inet_pton/call-graph=dwarf,max-stack=4/
>> perf trace --no-syscalls --max-stack 4 -e probe_libc:inet_pton/call-graph=dwarf/ ping -6 -c 1 ::1
>> Value too large for defined data type
>> [root@jouet ~]#
>>
>> Grrr.
>
>
> Got this one fixed with the following patch:
>
> commit b78278e11f6992ca348a4b96aad3b2c0a9ecf0f0

[...]

>
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index efa2e629a669..8f971a2301d1 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -731,14 +731,14 @@ static void apply_config_terms(struct perf_evsel *evsel,
> struct perf_evsel_config_term *term;
> struct list_head *config_terms = &evsel->config_terms;
> struct perf_event_attr *attr = &evsel->attr;
> - struct callchain_param param;
> + /* callgraph default */
> + struct callchain_param param = {
> + .record_mode = callchain_param.record_mode,
> + };
> u32 dump_size = 0;
> int max_stack = 0;
> const char *callgraph_buf = NULL;
>
> - /* callgraph default */
> - param.record_mode = callchain_param.record_mode;
> -
> list_for_each_entry(term, config_terms, list) {
> switch (term->type) {
> case PERF_EVSEL__CONFIG_TERM_PERIOD:

This patch works for me.
Here is the output on my s390x:

[root@s8360047 perf]# ./perf trace --no-syscalls --max-stack 4
-e probe_libc:inet_pton/call-graph=dwarf/ ping -6 -c 1 ::1
PING ::1(::1) 56 data bytes
64 bytes from ::1: icmp_seq=1 ttl=64 time=0.070 ms

--- ::1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.070/0.070/0.070/0.000 ms
0.000 probe_libc:inet_pton:(3ffa70c2060))
__GI___inet_pton (/usr/lib64/libc-2.26.so)
gaih_inet (inlined)
__GI_getaddrinfo (inlined)
main (/usr/bin/ping)
[root@s8360047 perf]# ./perf trace --no-syscalls --call-graph dwarf
-e probe_libc:inet_pton -- ping -6 -c 1 ::1
PING ::1(::1) 56 data bytes
64 bytes from ::1: icmp_seq=1 ttl=64 time=0.086 ms

--- ::1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.086/0.086/0.086/0.000 ms
0.000 probe_libc:inet_pton:(3ff93fc2060))
__GI___inet_pton (/usr/lib64/libc-2.26.so)
gaih_inet (inlined)
__GI_getaddrinfo (inlined)
main (/usr/bin/ping)
__libc_start_main (/usr/lib64/libc-2.26.so)
_start (/usr/bin/ping)
[root@s8360047 perf]#

[root@s8360047 perf]# ./perf trace --no-syscalls
-e probe_libc:inet_pton/call-graph=dwarf,max-stack=3/ ping -6 -c 1 ::1
PING ::1(::1) 56 data bytes
64 bytes from ::1: icmp_seq=1 ttl=64 time=0.066 ms

--- ::1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.066/0.066/0.066/0.000 ms
0.000 probe_libc:inet_pton:(3ffb82c2060))
__GI___inet_pton (/usr/lib64/libc-2.26.so)
gaih_inet (inlined)
__GI_getaddrinfo (inlined)
main (/usr/bin/ping)
__libc_start_main (/usr/lib64/libc-2.26.so)
_start (/usr/bin/ping)
[root@s8360047 perf]#

Not sure if this can work at all. Since dwarf stack unwinding is done in user space
the attr.sample_max_stack set to 3 is useless in this case.

Yout have my Tested-by.
--
Thomas Richter, Dept 3303, IBM LTC Boeblingen Germany
--
Vorsitzende des Aufsichtsrats: Martina Koederitz
Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294

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